Economic development and natural amenity: An econometric analysis of urban green spaces in China

Rapid urbanization and spontaneous economic development has brought about profound changes in urban landscapes throughout the world. The task of managing transforming urban landscapes, particularly urban green spaces, so as to provide sufficient natural amenity for increasing urban populations, is one of the critical challenges facing policy makers. However, little empirical evidence exists about the evolving path of urban green spaces along with economic development and urbanization. This study attempts to fill in this knowledge gap through an econometric analysis of panel data across 285 Chinese cities during a period of rapid urbanization and economic growth (2001–2010). The results point to the existence of an N-shaped environmental Kuznets curve (EKC) for an important aspect of environmental quality: urban green spaces. Urban green space coverage increases at the initial stage of economic development, and then it starts to decrease as GDP per capita exceeds RMB50,855 and then increases again at a high GDP per capita level (RMB107,558). Large elasticity (>1) is expected as GDP per capita grows to a higher level (beyond RMB128,095). By the end of 2010, 30% of Chinese cities are still located on the downward-sloping path and only four cities have attained elasticities greater than one. The findings present a challenging and pressing call for policy makers to effectively manage the tradeoffs between continuous economic development and better natural amenities.     

Carbon sinks in urban public green spaces under carbon neutrality: A bibliometric analysis and systematic literature review

Urban green spaces play essential roles in regulating the global carbon cycle and reducing carbon dioxide (CO₂) emissions. However, research on the carbon sequestration efficiency of urban public green spaces, which is closely related to the human settlement environment, has not received enough attention. Thus, we systematically analyzed the existing literature in the Web of Science core database using bibliometrics and network analysis combined with the CiteSpace visualization tool. The aim of this review was to elucidate the focus and development trend of research conducted between 2007 and 2022 on carbon sinks in urban public green spaces. Our results demonstrated that: 1) Numbers of related publications are increasing annually, indicating that the subject is receiving increasing global attention. Related research topics primarily focus on two aspects: carbon sink measurement methods and sustainable carbon sink design for urban public green spaces. 2) Methods for measuring and monitoring carbon sinks in the urban public green spaces include sample plot measurement, the assimilation method, the micrometeorological method, the remote sensing (RS) estimation method, and laboratory work. Most methods follow the forestry system approach and lack the methods and techniques to directly assess the carbon sink effectiveness of urban public green spaces. 3) Key factors affecting the carbon sink capacity of urban public green spaces are: plant species selection, plant community structure, green space characteristics, and maintenance management. 4) Future research should focus on encouraging public participation in the design of sustainable carbon sinks in urban public green spaces, advancing biodiversity research on carbon sinks in urban public green spaces, and enhancing the precision of measurements while addressing regional differences. This study contributes to the integration of research on the effectiveness of carbon sinks in urban public green spaces and provides a theoretical reference and guidance reduces prospective urban emission and achieves climate goals.     

An index to identify suitable species in urban green areas

This paper presents a method that allows sorting of tree and shrub species according to their suitability for planting in urban areas of Madrid (Spain). Suitability was determined from a weighted index for each species according to the severity of damage (biotic, abiotic, and anthropogenic; stem wounds are the main problem in trees, while dead plants are the most important problem in shrubs, seasonal flowers, and vines) and to risk, which was obtained from a new measure, observed Species per Green Area per Year (SAYs). The greater the number of damaged SAYs, the less suitable a species was considered for outdoor planting. For this purpose, 49 green areas corresponding to 141 ha were sampled during 2005–2008. The tree species least recommended for planting include Robinia pseudoacacia, Ulmus sp., Acer negundo, Platanus × hybrid, Populus Boolleana. The shrubs least recommended for planting are Nerium oleander, Cotoneaster sp., Euonymus europaeus, Pyracantha coccinea, and Pittosporum tobira. Statistical analysis reveals that native species have a lower percentage of damaged SAYs than non-native species.     

Challenges of urban green space management in the face of using inadequate data

Effective urban planning, and urban green space management in particular, require proper data on urban green spaces. The potential of urban green spaces to provide benefits to urban inhabitants (ecosystem services) depends on whether they are managed as a comprehensive system of urban green infrastructure, or as isolated islands falling under the responsibility of different stakeholders. Meanwhile, different urban green space datasets are based on different definitions, data sources, sampling techniques, time periods and scales, which poses important challenges to urban green infrastructure planning, management and research. Using the case study of Lodz, the third largest city in Poland, and an additional analysis of 17 other Polish cities, we compare data from five publicly available sources: 1) public statistics, 2) the national land surveying agency, 3) satellite imagery (Landsat data), 4) the Urban Atlas, 5) the Open Street Map. The results reveal large differences in the total amount of urban green spaces in the cities as depicted in different datasets. In Lodz, the narrowly interpreted public statistics data, which are aspatial, suggest that green spaces account for only 12.8% of city area, while the most comprehensive dataset from the national land surveying agency reveals the figure of 61.2%. The former dataset, which excludes many types of green spaces (such as arable land, private and informal green spaces), is still the most commonly used. The analysis of the 17 other cities confirms the same pattern. This results in broader institutional failures related to urban green infrastructure planning, management, and research, including a lack of awareness of green space quality (e.g. connectivity) and benefits (ecosystem services), and the related political disregard for urban green spaces. Our comparison suggests that a better understanding of green space data sources is necessary in urban planning, and especially when planning urban green infrastructure.     

The potential of school green areas to improve urban green connectivity and multifunctionality

Urban green infrastructure supports resilience in cities and promotes sustainable resource management. Small green areas, including school green areas (SGAs), are an important component of urban green infrastructure, playing a key role in supplying cities with educational services. This article describes how SGAs can amplify an urban green area's connectivity and multifunctionality. The analysis was performed in Bucharest as a case study. A survey based on questionnaires was used to obtain data regarding green spaces within public schools. A total of 411 administrators from 461 public schools participated in the survey for a response rate of 89.1%. Information from the questionnaires was augmented with spatial data of SGAs and public green spaces, i.e., parks and city gardens. Using parametric and nonparametric statistical analysis, we first identified the variables that determine an SGA's presence and size. Potential connectivity assessment results showed that most of the schools that lack or have small-sized SGAs have the possibility to cover their green space deficit by developing activities within nearby public green spaces. A structural connectivity assessment of SGAs toward other public urban green areas revealed that SGAs are an important element of the urban environment by serving as stepping stones to species flow. The multifunctionality of the SGAs was emphasized through the educational services they provide, being involved in pupils’ daily activities. The increased connectivity and multifunctionality of urban green infrastructure through small, specialized green areas, such as SGAs, is an indicator of the fact that such areas can be used to ameliorate the deficit of green space in major urban areas.     

Soundscapes of urban parks: An innovative approach for ecosystem monitoring and adaptive management

Urban foresters are addressing the challenge of urban biodiversity loss through management plans in the context of rapid urbanization. Protecting the integrity of the urban ecosystem requires long-term monitoring and planning for resilience as well as effective management. The soundscape assessment has attracted attention in this field, but applying the soundscape assessment in urban ecological monitoring requires a protocol that links soundscapes to the impact of resource management on biodiversity over time. The effective processing and visualization of large-scale data also remains an important challenge. The aim of this study was to better understand the relationship between soundscape and physical environment, and examine the feasibility of this innovative soundscape approach in highly urbanized areas. Soundscape recordings were collected for 20 urban parks twice on 4 consecutive days in Spring. A total of 691,200 min of sound material were automatically obtained. In order to track the spatio-temporal patterns of a soundscape and determine its potential suitability for ecosystem monitoring, our study characterized soundscape information by adopting 4 widely used acoustic indices: acoustic diversity index (ADI), bioacoustic index (BIO), normalized difference vegetation index (NDSI), and power spectral density (PSD). Daily patterns of PSD have provided a potential connection between soundscapes and bird songs, and 1–2 kHz presented a similar pattern that was linked to human activity. Through further modeling, we tested the relationship of soundscapes to physical environment characteristics. The results showed the importance of habitat vegetation structure for acoustic diversity. More vertical heterogeneity, with an uneven canopy height or multilayered vegetation, was associated with more acoustic diversity. This suggests that clearing ground cover may have a significant negative impact on wildlife. Our results suggest that soundscape approaches provide a way to quickly synthesize large-scale recording data into meaningful patterns that can track changes in bird songs and ecosystem conditions. The proposed approach would enable regular assessment of urban parks and forests to inform adaptive planning and management strategies that can maintain or enhance biodiversity.     

Analyzing spatial inequalities in use and experience of urban green spaces

As cities become more densely populated, urban green spaces (UGS) are increasingly important due to the environmental and social benefits they provide. Cities are confronted with the challenge of equitable supply of high-quality urban green that meets the demand of residents. This is particularly relevant in lower-income neighborhoods, which tend to suffer from the lowest supply of (high quality) UGS. In this paper, we perform spatial analysis on the responses of an online user survey to explore how UGS frequency of use, choice, and satisfaction differ by use pattern and place of residence in the Brussels Capital Region. Additionally, we identify the “push-pull” factors of individual UGS by identifying the desirable (pull) and undesirable (push) qualities that may attract or repel the use of a UGS. We find that use pattern is related to choice and experience of UGS. Compared to people who use UGS for social purposes, those who use UGS for nature-oriented reasons more often choose to visit UGS that are substantially farther from their home but are more often satisfied with the UGS they use. Our findings also show that respondents living in areas with higher proportions of disadvantaged groups tend to travel substantially farther to reach their UGS and are more often dissatisfied with the UGS they visit. Finally, our push-pull analysis indicates that characteristics that are important to nature-oriented users, such as quietness and calmness, are often more negatively experienced in dense city center UGS. Our research thus demonstrates the need to bring more green, particularly green that elicits a feeling of “naturalness”, to areas of the city where low green space quality and quantity overlap with areas inhabited by vulnerable populations.     

Enhancing plant diversity and mitigating BVOC emissions of urban green spaces through the introduction of ornamental tree species

Promoting the plant diversity of urban green spaces is crucial to increase ecosystem services in urban areas. While introducing ornamental plants can enhance the biodiversity of green spaces it risks environmental impacts such as increasing emissions of biogenic volatile organic compounds (BVOCs) that are harmful to air quality and human health. The present study, taking Qingdao City as a case study, evaluated the plant diversity and BVOC emissions of urban green spaces and tried to find out a solution to increase biodiversity while reducing BVOC emissions. Results showed that: (1) the species diversity and phylogenetic diversity of trees in urban green spaces were 22% and 16% lower than rural forest of this region; (2) urban areas had higher BVOC emission intensity (2.6 g C m⁻² yr⁻¹) than their rural surroundings (2.1 g C m⁻² yr⁻¹); (3) introducing the selected 11 tree species will increase 15% and 11% of species diversity and phylogenetic diversity, respectively; and (4) the BVOC emissions from green spaces will more than triple by 2050, but a moderate introduction of the selected low-emitting trees species could reduce 34% of these emissions. The scheme of introducing low-emitting ornamental species leads to a win–win situation and also has implications for the sustainable green space management of other cities.     

Estimating urban green space production in the macroeconomy: From public goods to a profitable method of investment

Accompanied by long-term urbanization, the Chinese production of urban green space (UGS) is gradually transforming into a land operation strategy for local governments to maximize land lease revenue. This paper presents empirical research on different types of investment, urban space, and gross domestic product (GDP) with a simultaneous equations model (SEM) of econometrics to test the capital circulation and accumulation of UGS production in China. The regression results strongly support our hypothesis that UGS production contributes to GDP growth and that there is an economic feedback loop between them. One billion RMB of the government’s fixed-asset investments produces 0.899 km² UGS in the long term, and this UGS yields 1.749 billion RMB tertiary industry GDP in return. Thus, the total return rate in the representative economic chain of “fixed-asset investment-UGS-tertiary industry GDP” is greater than 174.9%. However, this percentage also reveals the weakness of providing rewards in maximizing land lease relative to urban industrial, traffic and residential spaces. We also estimate the lagged correlation coefficient with a rational distributed lag model, showing that the production of UGS has a longer-term and more profitable influence on tertiary industry GDP than on secondary industry GDP. The long-run effect of investment on UGS lasts for approximately five years in producing secondary industry GDP and more than ten years in producing tertiary industry GDP. A continuous increase in fixed-asset investments in UGS would achieve a balanced return rate (100%) and start to produce profits after the 4th year, according to the economic chain of ΔFAI-ΔUGS-ΔTGDP.     

Evaluating naturalness and functioning of urban green infrastructure

Evaluating the state of urban green infrastructure (UGI) is a basic step to reach urban sustainability. Two indicators were used to evaluate 89 UGI sites in Zaragoza, a medium-sized city in NE Spain: Naturalness (Nat), related to the area covered by natural components; Functioning (Fun), related to the area showing natural hydro-geomorphological features. Complementarily, 15 biophysical and social variables were used to characterize these sites. A principal component analysis (PCA) was performed to group variables and types of UGI, while linear regressions and ANOVAs were applied to identify relationships between UGI characteristics, Nat and Fun.The Zaragoza UGI was dominated by artificial regular sites. Most sites (73%) have low-medium values of Nat and Fun. They were mostly flat urban parks with very regular forms located in the most densely urbanized zones, and 20% of the sites have high values of Nat and Fun, corresponding to well-conserved natural areas, either unchanged or slightly transformed. Only 3 sites displayed high Nat values and low Fun values. No sites had high Fun values and low Nat values. These groups of UGI sites were mostly distributed along the first axis of the PCA which represented the natural and heterogeneous forms versus regularity and flatness features. The UGI sites scattered throughout the second axis represented a gradient from paved to vegetated sites. Both Nat and Fun were positively correlated with area, natural subsoil and the area covered by vegetation but negatively with artificial soil, regularity and flatness after the linear regressions and ANOVAs.These results show that Nat and Fun are effective indicators to assess UGI sites. Minimizing regularity of design, preserving the natural topological relief, and restricting the area covered by artificial components are suggested to achieve a balanced representation of ecosystem processes, functions, and services within the UGI network of a city.     

Aesthetic growth of a native tree species with desirable characteristics for urban green areas in arid and semiarid environments

Having an aesthetic form is one of the desirable aspects of trees used to create or reforest urban green areas, which is often achieved by procedures that require a great effort. The understanding of factors affecting the architecture of plants in natural conditions may be useful to promote a desirable shape during the growth process. Under the hypothesis that trees in high luminosity conditions have a more aesthetical growth, in this study we explore the relationship between plant shape and photosynthetically active radiation (PAR) in Bursera fagaroides, a characteristic species of the tropical dry forest and xerophytic shrub-lands useful for urban green areas in semiarid environments. To evaluate trees shape we calculate a symmetry index (I_S) by using two diameters of the crown, perpendicular to each other, and the total height. Measurements were made over three periods (before, during and after the growth period); and PAR was also measured for each tree. Linear regressions were used to analyze the relationship between the symmetry of trees and PAR received during the growth period. The post-growth symmetry of trees showed a positive relationship with the PAR received by trees during the growth period, suggesting that PAR effects can be harnessed to develop post-germination strategies for the production of trees with a more aesthetical growth in the studied species. Effect of PAR on the shape of plants may represent a practical option to promote aesthetical growth of trees and shrubs with importance for creation and restoration of urban green areas.     

Evaluating the risk of accessing green spaces in COVID-19 pandemic: A model for public urban green spaces (PUGS) in London

The pandemic caused by SARS-CoV-2 (COVID-19) at the beginning of 2020 has restricted the human population indoor with some allowance for recreation in green spaces for social interaction and daily exercise. Understanding and measuring the risk of COVID-19 infection during public urban green spaces (PUGS) visits is essential to reduce the spread of the virus and improve well-being. This study builds a data-fused risk assessment model to evaluate the risk of visiting the PUGS in London. Three parameters are used for risk evaluation: the number of new cases at the middle-layer super output area (MSOA) level, the accessibility of each public green space and the Indices of Multiple Deprivation at the lower-layer super output area (LSOA) level. The model assesses 1357 PUGS and identifies the risk in three levels, high, medium and low, according to the results of a two-step clustering analysis. The spatial variability of risk across the city is demonstrated in the evaluation. The evaluation of risk can provide a better metric to the decision-making at both the individual level, on deciding which green space to visit, and the borough level, on how to implement restricting measures on green space access.     

Shortcuts in urban green spaces: An analysis of incidental nature experiences associated with active mobility trips

Nature experiences and active mobility both deliver well-being and health benefits but have rarely been investigated together. Conceptualizations of nature experiences largely focus on intention, and the planned motivations for visits. However, nature experiences can also be perceived incidentally, if daily living activities like trips are encouraged towards green spaces. In a public participation GIS (PPGIS) survey of five local districts in Copenhagen, 517 respondents mapped 688 places along their walking or cycling shortcut trips through green spaces. This study investigated what types of green space provide opportunities for such shortcuts, what incidental nature experiences can be perceived there and the different responses of pedestrians and cyclists. This study also explored the relation between incidental nature experiences and green space characteristics in the form of tree cover density. Lastly, this study explored whether frequent short trips through green spaces relate to nature connectedness. The results show that public green spaces and urban cemeteries in Copenhagen allow for such shortcut trips. Enjoyment of pleasing views is the most perceived incidental nature experience. Pedestrians are found more prone to experience surprise, inspiration and emotion, while cyclists prefer shortcuts close to water, which they value highly. The study suggests that high tree cover density is key to delivering incidental nature experiences. Furthermore, the study shows that people who make frequent trips through green spaces have higher levels of nature connectedness, indicating that incidental nature experiences during shortcut trips trigger the reconnection of people and nature. The study’s results support a synergistic approach to integrating green spaces and active mobility in planning and management practice, where incidental nature experiences should be emphasized.     

The role of green spaces and their management in a child-friendly urban village

Environmental child-friendliness is affected by how built environments and green spaces are planned and designed, but also by their ongoing management, including both development and maintenance. This study examined children’s perspectives on their local environments with focus on green spaces and their management in an urban village. Five groups totalling 16 children aged 10–11 were interviewed through child-led walks. Both the qualities of the village as a whole and of specific places within it added to the child-friendliness of the local environment. The children showed planned and managed spaces including playgrounds and parks, and unmanaged places such as abandoned gardens. They found many qualities in multifunctional planned places with a varied, rich content. In unmanaged areas the lack of management was seen as positive for exploration, play possibilities and for the place to be children’s own. The findings suggest that children’s perspectives can play an important role not only in planning and design, but also in the ongoing process of landscape management, including the provision of more variation in local green spaces.     

Influence of green spaces on environmental satisfaction and physiological status of urban residents

Influence of urban green spaces on human was evaluated with subjective questionnaires as well as physiological measurements. Five sample plots vary in color, size and scent of major plants and one no-vegetation area located in Shanghai Botanical Garden, China were chosen. 249 questionnaires on subjective satisfaction evaluation were collected; in addition to 64 visitors took the measurement of physiological parameters like Electroencephalogram (EEG) and Electrocardiogram (ECG). Questionnaire results show that color is one of the most important factors which affect the overall satisfaction of people with their vegetation environment. The way how people perceive vegetation environment was probed by PCA analysis. Age difference analysis show children and elder people presented higher satisfaction with vegetation environment than adults. Significant negative correlation between the ratio of low-frequency to high-frequency (LF/HF) values in heart rate variability (HRV) analysis and satisfaction values indicated HRV may be an effective parameter for green spaces influence evaluation.     

Systems approach to the sustainable management of urban public parks

Public green spaces are becoming crucial components of any sustainable community because of their multiple ecological, economic and sociocultural benefits. More efforts are being directed towards creating livelier spaces. Unfortunately, there is less adequate attention to their long-term upkeep. Both research and practice focus more on design aspects of public spaces and parks than on their management. Realising the importance of management, this research is addressing this recognised gap by providing a comprehensive study of the management process. It draws on previous public spaces and green spaces management literature to define four main management requirements: being responsive to context, setting direction, managing performance and dealing with resources. Guided by the systems approach and sustainability concepts, the management requirements and process are presented in a framework that combines different levels of management with the internal dynamics of the public park. This framework can be a useful tool for researchers, designers, decision-makers and managers.     

Classification of institutional barriers affecting the availability,accessibility and attractiveness of urban green spaces

The main goal of this article is to identify and classify institutional barriers which prevent the use of urban green spaces (UGS) at three levels: availability (whether a UGS exists), accessibility (whether it is physically and psychologically accessible, e.g., not fenced off), and attractiveness (whether it is attractive enough for potential users to visit). We reviewed the impacts on UGS provision exerted by different actors (individuals, formal and informal groups, community councils, city authorities, national governmental and non-governmental organizations), along with the relevant institutional foundations of those impacts. As a result, we identified and classified the different barriers for which these actors are responsible in the case of fifteen UGS types in our case study city, Lodz (Łódź) in Poland. The main barriers at different levels concern conflicting interests, physical barriers (private green spaces), and the lack of funds, together with legal and governmental failures (public green spaces). These barriers result from the different actors’ mandates or lack thereof. Our analysis has implications for the operationalization of UGS availability, accessibility and attractiveness, and, in particular, for mapping UGS and setting the relevant indicators and thresholds for UGS availability, accessibility and attractiveness.     

Responses of four hornet species to levels of urban greenness in Nagoya city,Japan: Implications for ecosystem disservices of urban green spaces

Although there is a common trend towards increasing green space in modern cities, urban green spaces provide not only ecosystem services but also disservices for urban dwellers. However, the relationship between urban greenness and ecosystem disservices has been poorly examined. We aimed to understand the effect of greenness level on the abundance and species composition of hornets – critical pests in Japan and to identify the best spatial scale for estimating their abundance with reference to greenness levels. We used a dataset that contained eight years of abundance data for four hornet species at 11 sites in Nagoya city. The levels of greenness around the hornet sampling points were measured using averages from the Normalized Difference Vegetation Index (NDVI) with radiuses of 0.1–10.0 km. We analysed the relationship between abundance and species composition of hornets and NDVI at different spatial scales using generalized linear mixed models. Higher NDVI values positively affected the abundance of all the hornet species except Vespa analis. The abundances were estimated most effectively using the NDVI average with a 1–2 km radius for all species. The species composition of hornets drastically changed along the gradient of NDVI values; V. mandarinia was dominant in greener areas (over 0.2–0.3 NDVI average with a 2 km radius) and V. analis in less green areas (below 0.2–0.3 NDVI average). Our study showed that the abundance and species composition of hornets were both strongly associated with the level of urban greenness. This suggests that increases in the greenness of urban areas can increase hornet abundance and alter the species composition of hornets; a more aggressive species, V. mandarinia, may also increase in urban areas, although V. analis is currently the most critical species according to regional consultants. Balancing ecosystem services and disservices has become crucial for the planning and management of green spaces, particularly when urban green space increases. We also demonstrate how human tolerance towards wildlife may have to be improved in order to live in greener environment where wildlife can be expected.     

Green justice in the city: A new agenda for urban green space research in Europe

In this short communication, we discuss European urban green space (UGS) research from an environmental justice perspective. We show that European UGS scholarship primarily focuses on functional values and managerial aspects of UGS, while paying less attention to equity in the enjoyment of and decision-making around UGS. On this basis we discuss potentials for European urban green space research to take up a more explicit environmental justice framing to shed much-needed light on injustices in European cities and inspire change in policy and practice.     

RFID-plants in the smart city: Applications and outlook for urban green management

A city may become smart and green through strategic deployment of Information and Communication Technology infrastructure and services to achieve sustainability policy objectives in which trees have to be involved. Plants not only constitute green space useful to contrast urban pollution effects or provide ecosystemic benefits to residents but they can also be used as bioindicators and their involvement in communication networks can represent a significant contribution to build a smart, green city. The concept of the Internet of Things (IoT) envisages that objects that surround us will be connected and there are no reasons to exclude urban trees from among the “wired object”. Radio frequency identification devices (RFID) may represent a prerequisite of IoT application and they can be used for tree protection and management, thanks to tagging experience carried out on various plant species. RFID tags can be easily associated with plants, externally or internally. This latter approach is particularly indicated if the identification of trees needs to be secured since its production, eliminating the risk of tag losses or removal. Interesting applications may be derived by implementing RFID tags in biomonitoring systems in order to guarantee a real-time data communication in which tags may act as antennas for multifunctional green spaces. Moreover, the virtualization of green areas using sensors and mobile devices can lead to the desktop management of the urban green with the possibility of implementing a real-time navigation throughout the areas. A complex relational network in which data can be collected thanks to geospatial methods can be integrated by an IoT approach in which RFID-plants can play a significant role.